Remove obsolete --harmony-promises flag from tests.

test/mjsunit/es6/debug-promises-uncaught-uncaught.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-promises --expose-debug-as debug
+// Flags: --expose-debug-as debug
 
 // Test debug events when we only listen to uncaught exceptions and
 // there is a catch handler for the exception thrown in a Promise.
 // We expect an Exception debug event with a promise to be triggered.
 
 Debug = debug.Debug;
 
 var log = [];
 var step = 0;
 
@@ skipping 29 matching lines @@
     // and this listener to be executed after the main script is finished.
     print("Unexpected exception: " + e + "\n" + e.stack);
     quit(1);
   }
 }
 
 Debug.setBreakOnUncaughtException();
 Debug.setListener(listener);
 
 log.push("end main");